Currently when set_id_regs encounters a problem checking validation of
writes to feature registers it uses an immediately fatal assert to report
the problem. This is not idiomatic for kselftest, and it is also not great
for usability. The affected bitfield is not clearly reported and further
tests do not have their results reported.

Switch to using standard kselftest result reporting for the two asserts
we do, these are non-fatal asserts so allow the program to continue and the
test names include the affected field.

Signed-off-by: Mark Brown <broonie@kernel.org>
---
 tools/testing/selftests/kvm/arm64/set_id_regs.c | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/kvm/arm64/set_id_regs.c b/tools/testing/selftests/kvm/arm64/set_id_regs.c
index b61942895808..5837da63e9b9 100644
--- a/tools/testing/selftests/kvm/arm64/set_id_regs.c
+++ b/tools/testing/selftests/kvm/arm64/set_id_regs.c
@@ -409,6 +409,7 @@ static uint64_t test_reg_set_success(struct kvm_vcpu *vcpu, uint64_t reg,
 	uint8_t shift = ftr_bits->shift;
 	uint64_t mask = ftr_bits->mask;
 	uint64_t val, new_val, ftr;
+	bool match;
 
 	val = vcpu_get_reg(vcpu, reg);
 	ftr = (val & mask) >> shift;
@@ -421,7 +422,10 @@ static uint64_t test_reg_set_success(struct kvm_vcpu *vcpu, uint64_t reg,
 
 	vcpu_set_reg(vcpu, reg, val);
 	new_val = vcpu_get_reg(vcpu, reg);
-	TEST_ASSERT_EQ(new_val, val);
+	match = new_val == val;
+	if (!match)
+		ksft_print_msg("%lx != %lx\n", new_val, val);
+	ksft_test_result(match, "%s valid write succeeded\n", ftr_bits->name);
 
 	return new_val;
 }
@@ -433,6 +437,7 @@ static void test_reg_set_fail(struct kvm_vcpu *vcpu, uint64_t reg,
 	uint64_t mask = ftr_bits->mask;
 	uint64_t val, old_val, ftr;
 	int r;
+	bool match;
 
 	val = vcpu_get_reg(vcpu, reg);
 	ftr = (val & mask) >> shift;
@@ -449,7 +454,10 @@ static void test_reg_set_fail(struct kvm_vcpu *vcpu, uint64_t reg,
 		    "Unexpected KVM_SET_ONE_REG error: r=%d, errno=%d", r, errno);
 
 	val = vcpu_get_reg(vcpu, reg);
-	TEST_ASSERT_EQ(val, old_val);
+	match = val == old_val;
+	if (!match)
+		ksft_print_msg("%lx != %lx\n", val, old_val);
+	ksft_test_result(match, "%s invalid write rejected\n", ftr_bits->name);
 }
 
 static uint64_t test_reg_vals[KVM_ARM_FEATURE_ID_RANGE_SIZE];
@@ -489,7 +497,11 @@ static void test_vm_ftr_id_regs(struct kvm_vcpu *vcpu, bool aarch64_only)
 		for (int j = 0;  ftr_bits[j].type != FTR_END; j++) {
 			/* Skip aarch32 reg on aarch64 only system, since they are RAZ/WI. */
 			if (aarch64_only && sys_reg_CRm(reg_id) < 4) {
-				ksft_test_result_skip("%s on AARCH64 only system\n",
+				ksft_print_msg("%s on AARCH64 only system\n",
+					       ftr_bits[j].name);
+				ksft_test_result_skip("%s invalid write rejected\n",
+						      ftr_bits[j].name);
+				ksft_test_result_skip("%s valid write succeeded\n",
 						      ftr_bits[j].name);
 				continue;
 			}
@@ -501,8 +513,6 @@ static void test_vm_ftr_id_regs(struct kvm_vcpu *vcpu, bool aarch64_only)
 
 			test_reg_vals[idx] = test_reg_set_success(vcpu, reg,
 								  &ftr_bits[j]);
-
-			ksft_test_result_pass("%s\n", ftr_bits[j].name);
 		}
 	}
 }
@@ -839,7 +849,7 @@ int main(void)
 		ID_REG_RESET_UNCHANGED_TEST;
 	for (i = 0; i < ARRAY_SIZE(test_regs); i++)
 		for (j = 0; test_regs[i].ftr_bits[j].type != FTR_END; j++)
-			test_cnt++;
+			test_cnt += 2;
 
 	ksft_set_plan(test_cnt);
 

-- 
2.47.3

Hi Mark,

On 12/19/25 19:28, Mark Brown wrote:
> Currently when set_id_regs encounters a problem checking validation of
> writes to feature registers it uses an immediately fatal assert to report
> the problem. This is not idiomatic for kselftest, and it is also not great
> for usability. The affected bitfield is not clearly reported and further
> tests do not have their results reported.
> 
> Switch to using standard kselftest result reporting for the two asserts
> we do, these are non-fatal asserts so allow the program to continue and the
> test names include the affected field.
> 
> Signed-off-by: Mark Brown <broonie@kernel.org>
> ---
>  tools/testing/selftests/kvm/arm64/set_id_regs.c | 22 ++++++++++++++++------
>  1 file changed, 16 insertions(+), 6 deletions(-)

This one also looks good to me. I'm not aware of why the asserts have
been favoured previously though.

Reviewed-by: Ben Horgan <ben.horgan@arm.com>

Thanks,

Ben

On Fri, Jan 02, 2026 at 02:45:04PM +0000, Ben Horgan wrote:
> On 12/19/25 19:28, Mark Brown wrote:
> > Currently when set_id_regs encounters a problem checking validation of
> > writes to feature registers it uses an immediately fatal assert to report
> > the problem. This is not idiomatic for kselftest, and it is also not great

> This one also looks good to me. I'm not aware of why the asserts have
> been favoured previously though.

The older KVM selftests and the KVM specific selftest framework don't
work with the kselftest framework inside the test programs and instead
just run a single test within each test program and die immediately if
there's some issue.  This is fine so long as each test only does one
thing but falls apart when you've got multiple tests in a single program
like this one, there the kselftest framework helps a lot.  It looks like
the program is mixing the two idioms.